One of the few benefits of consumerism is its ability to empower buyers for the greater good. As the public demands more transparency in food production, so too have animal agriculture shareholders felt an urge to keep tabs on their supply chains. One way this has been accomplished is through various third-party auditing programs like the Common Swine Industry Audit (CSIA) in the United States.

The CSIA evaluates pig welfare based on three types of measures:

• Animal-based measures such as body condition and lameness scores;
• Resource-based measures such as space allowance and flooring type; and
• Management-based measures such as written protocols and employee training.

Rather than observing all pigs on a farm, the CSIA includes just enough pigs to achieve 95% confidence that at least one animal within the sample is identified as having the welfare issue being measured. This means that the auditor observes an increasingly smaller proportion of pigs as the total population of pigs on the farm increases. For example, on a farm with 50 pigs, all 50 pigs would be observed, while on a farm with 5,000 pigs, 289 pigs — just 6% — would be observed.

Although the CSIA shares similarities with other nationally implemented audits like the Welfare Quality program in Europe, its accuracy hadn’t been measured prior to this study. To assess this, the study’s authors evaluated close to 240,000 pigs across 60 U.S. farms between October 2022 and July 2023. Two unidentified companies, one based in the Midwest and another in the Southeast, agreed to have data collected from their farms for the study.

Auditing The Audit

Data was gathered in relation to four production stages:

• Sow farm: where female pigs give birth and nurse their piglets, who are weaned at about three weeks of age
• Nursery farm: where newly weaned pigs are housed until they reach the finishing stage at around nine to 11 weeks of age
• Wean-to-finish farm: where newly weaned pigs are raised to market weight
• Finishing farm: where pigs from nursery farms are raised to market weight

For the study, wean-to-finish and finishing farm data was combined, resulting in datasets for 20 sow farms, 10 nurseries, and 30 finishing farms across the two companies.

Data was collected by auditors certified through the Professional Animal Auditor Certification Organization. The auditors used two sampling methods:

• Total inventory method: All animal-based measures were recorded for all pigs on the farm.
• CSIA method: Animal-based measures were recorded for the proportion of pigs determined by the CSIA’s statistical method. All production stages, housing types (stalls or pens), rooms, and barns were represented within that minimum number.

Each animal-based measure, such as abscesses, tail bites, severe scratches, and hernias, was scored as either a one (present) or zero (absent).

Is The Common Swine Industry Audit Accurate Enough?

Regardless of production stage, average occurrence scores were lower for the majority (57% to 89%) of animal-based measures when the CSIA method was used.

• For sow farms, the CSIA method found a lower occurrence of severe lameness, low body condition score, abscesses, open wounds, severe scratches, prolapses, vulva lesions, and shoulder sores.
• In nurseries, the CSIA method found a lower occurrence of severe lameness, abscesses, open wounds, and hernias.
• On finishing farms, the CSIA method found a lower occurrence of severe lameness, abscesses, open wounds, tail bites, prolapses, and vulva lesions.

Based on the total inventory method, occurrence rates for these welfare issues were generally low (less than 1%). However, the fact that the CSIA consistently underestimated them calls into question its reliability in accurately reporting the well-being of pigs on U.S. farms.

Study Limitations

Having only two companies participate was a significant limitation. Because of this, the only states included in the study were Iowa, Virginia, and North Carolina. Although farmed pig production is concentrated in the Midwest, regions such as the Northeast and Southwest weren’t represented. Furthermore, auditors weren’t required to undergo reliability testing and so observer bias wasn’t accounted for.

Takeaways

The authors are hopeful that their study can be used as an assessment in and of itself. In time, their findings can potentially be used to refine tools like the CSIA in a way that benefits farmed animals and consumers alike. While the CSIA may work as a broad estimate of pig welfare, it’s in the consumer’s power to demand more out of metrics to ensure that farms can actively address issues.